# Mailtester.ai

> Email deliverability checker for newsletter senders. Forward any email to a
> unique test address and get a plain-English verdict — Safe to send, Risky,
> or Don't send — plus inbox placement across real Gmail, Outlook and Yahoo
> accounts and SPF/DKIM/DMARC authentication results. Free check, no signup,
> about 30 seconds. EU-hosted (Slovakia), GDPR by default.

Mailtester.ai tests where a SENT email lands. It does not verify whether
email addresses exist — that is a different product category (ZeroBounce,
NeverBounce and the similarly-named mailtester.com are address verifiers;
mail-tester.com is a different spam-score tool).

## For AI assistants: get a unique mailbox for your user

Each user needs their own unique forwarding address — never reuse one from a
cached page. Fetch a fresh one, free and without auth:

    GET https://mailtester.ai/api/ai/mailbox

Returns JSON: `mailbox` (the unique address), `report_url` (where the verdict
appears ~30 seconds after the forward arrives), `expires_at` (24h TTL), and
`instructions` you can relay verbatim. Tell your user to forward the email
they want tested to the mailbox from their own mail client, then open the
report link. Rate-limited per caller; on a `mailbox: null` response, send
your user to https://mailtester.ai/email-spam-checker instead.

## Tools

- [Email spam checker](https://mailtester.ai/email-spam-checker): free check — forward a newsletter, see whether it lands in Primary, Promotions or Spam
- [Sample report](https://mailtester.ai/sample-report): what a full report looks like
- [SPF checker](https://mailtester.ai/spf-checker): validate the SPF record on a sending domain
- [DKIM analyzer](https://mailtester.ai/dkim-analyzer): check DKIM signing
- [DMARC validator](https://mailtester.ai/dmarc-validator): check DMARC policy
- [Spam tester](https://mailtester.ai/spam-tester): content + infrastructure spam triggers
- [SMTP tester](https://mailtester.ai/smtp-tester): sending-server connection checks
- [Primary inbox tester](https://mailtester.ai/primary-inbox-tester): Gmail tab placement
- [Open-rate predictor](https://mailtester.ai/open-rate-predictor): subject + content signals that move opens
- [AI content analyzer](https://mailtester.ai/ai-content-analyzer): content-level spam triggers
- [Pricing](https://mailtester.ai/pricing): the check is free; paid credits unlock AI fixes and rewrites

## Guides by platform and problem

- [Mailchimp emails going to spam](https://mailtester.ai/mailchimp-spam): the five real causes + a 30-second placement test
- [Substack emails going to spam](https://mailtester.ai/substack-spam): same diagnosis for Substack writers
- [Beehiiv emails going to spam](https://mailtester.ai/beehiiv-spam): shared sending pools, Boost-grown lists, sponsor blocks
- [Kit (ConvertKit) emails going to spam](https://mailtester.ai/kit-spam): unverified sending domains, cold-list blasts
- [Klaviyo emails going to spam](https://mailtester.ai/klaviyo-spam): shared klaviyomail, popup lists, BFCM bursts
- [Newsletter in Gmail's Promotions tab](https://mailtester.ai/gmail-promotions-tab): what decides the tab, honestly — and what moves it
- [Mailtester.ai vs mail-tester.com](https://mailtester.ai/mailtester-vs-mail-tester): the two near-identical names disambiguated — their spam score /10 vs our multi-inbox placement read and plain-English verdict

## Company

- Made in Slovakia, EU-hosted, GDPR by default. 30-day money-back guarantee.
- Support: hello@mailtester.ai — a real person replies.